At present grain harvesting is carried out using combine harvesters, which thresh the grain in a threshing cylinder or rotor then separate out the grain from chaff, grain leavings, straw and weed seeds. The combine harvester keeps the grain and rejects the other material, which is left on the field. Its thresher breaks the grain from the stalk or pod. A degree of separation is achieved in rotary threshers by using apertures in the thresher tube which allow passage of grain. However the combine's separation process is not totally efficient, the straw portion includes grain, grain leavings, and chaff, and the grain portion includes chaff, grain leavings and straw. The straw portion is then usually passed along a straw walker to remove more grain from the straw. When the thresher is a cylinder and a concave, the concave has apertures to pass the grain portion, but again the straw portion is usually passed along a straw walker to remove additional grain from the straw. The grain portion, which in combines includes chaff, grain, grain leavings and weed seeds, are then passed through a sieve with air blowing upwards. This is called the shoe and includes the aspiration (blowing) and sieve (cleaning) apparatus. The grain falls downward, while chaff, grain leavings and weed seeds and any straw are blown upward. Chaff, grain leavings, straw and weed seeds are left as waste by-products in the field, while the grain is transported to storage. Thus the economic value of chaff, grain leavings and weed seeds for animal feed is lost. Moreover the present combine method spreads weed seeds through the fields, necessitating intensive, extensive and expensive pesticide and herbicide applications, whereas the new method collects chaff and weed seeds. The weed seeds are crushed thereby releasing their nutrients into chaff for animal feed.
The problem with chaff (and grain leavings and weed seeds) is simply that the farmer has enough problems at harvest without trying to handle chaff in addition to grain. The time and labor required to gather chaff, haul it to the farmyard and then mill it to destroy weed seeds are commonly just not available. Chaff on mixed farms is either browse fed in field or feedlot without milling. Weed seeds are spread through manure, and weed control is lost.
Other advantages of the new method compared to the present combining method are in a cleaner grain product, providing farmers with less dockage, higher prices and less freight demurrage. Total harvesting equipment will be less costly. Equipment depreciation is less because the automatic cleaning plant is separate and incurs less wear. The field unit is simpler because it has none of the cleaning and separating equipment of the combine. At present prices the yard plant and associated harvester together cost less than a new combine harvester.
Although the term `grain` is primarily regarded as cereal grain referring to the seeds of grasses including many domesticated species, it is not limited thereto in instant application, since combine harvesters may be used as well for oilseeds, legumes and other domesticated plants. The term `grain` is herein intended to cover besides the usual definition, all crops harvestable by combine harvesters, especially but not limited to all prairie crops including small grains, and specifically including the major popular crops of alfalfa, barley, beans, buckwheat, canola, clover, corn (maize), flax, grass (most varieties), lentils, lespedeza, millet, mustard, oats, (edible) peas, rice, rye, sorghum, soybeans, sunflower, (birdsfoot) trefoil, vetch, and wheat, which are regularly harvested by combines. As those in the art appreciate the above list is indicative rather than restrictive in nature, and other crops harvestable by combine harvester are covered by the term `grain` as understood in the broad sense. The present invention is applicable to all combine harvestable crops which are referred to as `grain` herein.
The new method has several substantial advantages over current practice. At present combines harvest grain, and there is no alternative. A combine's equipment cost can exceed US $150,000. Under the new method the two unit equipment cost is US $95,000. The two units can be traded independently, thus giving farmers more flexibility in purchase decisions.
An environmental goal is to add value to waste. Chaff is currently left on the field as waste. Tests show chaff can be removed with no detrimental effects to soil. Chaff has value as animal feed (worth US $7.50 per acre). The new method removes chaff from the field cost effectively. There are other chaff collection methods available which are expensive, awkward, require more labor, but are not in common use.
Removal of chaff results in field advantages. Chaff rows, which may adversely affect minimal till seeding, are eliminated. Fertilizer application is often prevented from entering the soil by crop residue, which is mostly chaff by volume. The new method's removal of crop residue other than straw gives a cleaner field.
The new method produces cleaner grain reducing grain dockage and freight demurrage.
Grain loss from the combine's shoe is eliminated, which recovers an average of 1 to 2% more grain than conventional combine methods, which is a saving of about US $1,500 for a 700 acre field.
Combines return and spread weed seeds on the field creating weeds and weed patches. The new method doesn't spread weed seeds by collecting up to 250,000 weed seeds per acre with the chaff, thereby lowering pesticide (herbicide) and tillage requirements. The collected weed seeds are crushed in the method's yard plant, and their fat and protein adds to the collected chaff's feed value.
Volunteer growth is greatly reduced, both by decreasing grain loss and by collecting chaff. In dry years the small grain kernels, formerly left on the field, are collected with the chaff and enhance its feed value.
The new method is efficient. The field, or harvesting unit's has a larger grain bin (up to about three to four times as large as the combine's grain bin) and need be emptied every 10 acres, as opposed to 6 acres for a combine, even though the unit is collecting more material from the field. Since the yard plant has a consistent throughput, the grain cleaning unit, which is preferably electric, operates automatically, and can be left unattended. There is no need to keep up with the field harvesting process, as grain can be cleaned 24 hours per day.
The yard plant preferably contains a specifically designed roller mill which densifies the chaff, enhancing its value for transport and sale to feed lots.
A grain dryer can easily be incorporated into the yard plant.